There are times when this is easier than writing an event but its a bit daunting at first sight, especially if you don't know what you are looking for.

Since I've just done this as a PM for someone, thought I'd share with all. The specific goal was to delete a naval unit that had picked up a post-1910 replacement in a 1850s fleet. An annoying bug that seems to crop up now and then.

So:

First, make a copy of your .trn file (in case of errors).

Now open the .trn file, you'll find it somewhere like:

Maybe a bit different on your computer but it should be similar.

When the file is open do a search for a ship name that is the unit you want to delete.

You'll find an entry like this:

What we are interested is the line that starts {Unit}

Highlight everything from {Unit} down to the next {/Unit} - this will include 4 (maybe 3) subunits.

Simply delete that block.

Make sure there are no blank lines in the save file - ensure that the sequence {/unit} .. {unit} is what you can see.

Save, open the game and when you run that turn the unit should have been deleted.

An alternative is to identify the subunit that has the wrong type and try to correct this. Now this is trial and error (as the wiki is down and this has never been properly listed), but under a subunit you will see code like 1375 - its the second line after the text {subunit}

Now this code tells the computer what model type to use. If you look at the codes for the 4 subunits in the unit you'll see that one is different. Correct that to match the others. It should then re-appear as a sail ship.